Biological Illustration & Fine Art
What inspires my artwork and writing?
Nature and my studies of land snails and slugs.
Land snails and slugs are fascinating!
Stick with me and learn why.
An Introduction to Land Snails and Slugs
Iroquois Vallonia (Vallonia excentrica)
(c) Marla Coppolino
Land snails and slugs are members of the class Gastropoda, meaning “stomach-foot,” because they move upon a large, muscular ventral surface called a foot.
Gastropods include both land and aquatic snails, and are members of the phylum Mollusca, a diverse array of invertebrate animals including clams, mussels, limpets, chitons, tusk shells, octopuses and squid. Land snails and slugs are special in that they evolved from aquatic ancestors and possess many unique adaptations to survive in terrestrial habitats. They are in the group Pulmonata, meaning air-breathing.
Slugs are land snails that have evolved to not need a shell for protection. Slugs have instead evolved thicker mucus to prevent desiccation.
Scientists who study mollusks are called malacologists and the field of mollusk science is called malacology.
If you're wondering about those pest snails and slugs in your garden, they are invasive species, that is, not locally native and were accidentally brought from other places by anthropogenic means.
My interest is focused on locally native North American snails and slugs. They won't eat your garden.
Snails in the ecosystem
Locally native land snails serve an important role in the ecosystem. They eat very low on the food web, as most land snails will consume decaying vegetation like moist leaf litter, fungi, and sometimes eat soil directly. The land snail relies on a diet rich in calcium and other nutrients to support the growth and repair of its shell as well as its overall health.
Snails then in turn are consumed by a variety of predators that rely on snails for their calcium and other dietary needs. A great diversity of animal life feeds upon land snails, from insects to lizards and snakes, salamanders, birds and mammals. Some species of fireflies consume snails exclusively during their larval stage.
Good ecological literacy comes from understanding the nature as a whole. Many who appreciate the animal world tend to gravitate towards the “charismatic macrofauna” – amphibians, reptiles, birds, and mammals – or, towards the “beautiful” insects, like butterflies and dragonflies. Snails and slugs may be lowly and hidden from view, but the time taken to understand and appreciate them can bring an expanded view and deeper knowledge and appreciation for all of nature.
Copper button snail (Mesomphix cupreus)
(c)Marla Coppolino
Snails can be tiny!
Fact: About 95% of North American land snail species are the size of a lentil or smaller!
Here are some common snails found in leaf litter, placed on a USA penny for scale. These aren't baby snails -- they're fully grown adults.
Those ecosystem services take place on a micro-level. This is important because many other ecological interactions rely on nutrient turnover by snails and other tiny organisms.
Fully grown, adult snails on a USA penny.
(c)Marla Coppolino
Conservation
With the vital role that native land snails play in ecosystem, they deserve our respect, admiration, and efforts to preserve their habitat.
A major obstacle in deciding the status of snails is that we know so little about them. There are so many questions that land snail scientists have, such as “where do they live?”, “what are they eating”, “how many different species live here?”, and others. These questions lead to scientific investigations by malacologists, which help gain a better understanding of which types of snails are rare and may need to be identified as “threatened” or “endangered”.
Remember, if the snails are threatened or endangered, then it is likely that other animals that feed upon them are also susceptible to decline.
Land snails are animals of low vagility, that is, they are unable to disperse with any speed. Since they cannot escape changes in their environment, snails are very susceptible to acidic rainfall, road pollutant runoff, fertilizers, herbicides, lead, and other contaminants. Climate change is believed to adversely affect land snails and slugs, which as like the canaries in the coal mine.
The most endangered land snail in New York state is the Chittenango ovate amber snail (Novisuccinea chittenangoensis). There is only one existing population of this species in the world, near the base of Chittenango Falls, in New York. It is endemic to that area. See the accompanying fact sheet for more information, and this information from the US Fish & Wildlife Service, which reports on recent conservation efforts and successes in captive breeding and release of this species:
How you can be an advocate of snails
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Don’t use pesticides, herbicides, fertilizers, or other chemicals on your property,
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Keep part of your property in a natural state, that is, if a tree falls, leave it to decay. This makes a great habitat for snails.
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If you like to observe snails in nature, you can do so, and then leave them where you found them.
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If you turn over old logs and stone to find snails, be sure that you place these back just as you had found them.
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Spread the word to others that land snails are important to our ecosystem!
Resources and services
I lead snail walks and give educational presentations and workshops to all levels of age and interest.
Behold the Lowly Land Snail, by Marla Coppolino, in The Land Steward newsletter of the Finger Lakes Land Trust, April 2016
Nature and the Microcosm of Snails, by Marla Coppolino, in The Land Steward newsletter of the Finger Lakes Land Trust, October 2020
Perez, K.E. and J.R. Cordeiro, Eds. 2008. A Guide for Terrestrial Gastropod Identification. Marla L. Coppolino, Illus. American Malacological Society.
http://northamericanlandsnails.org/publications/AMS_Workbook_KEP_FINAL.pdf
Coppolino, M. L. (2010). Strategies for collecting land snails and their impact on conservation planning. American Malacological Bulletin, 28(2), 97-103.
https://doi.org/10.4003/006.028.0225
Glossy pillar snail (Cochlicopa lubrica) on a leaf (c)Marla Coppolino